CCNH and acute myeloid leukemia: Previous studies have shown that hyper-phosphorylation of RARα by CAK is associated with increased proliferation of acute myeloid leukemia (AML) and other types of cancer cells, whereas RA-induced RARα hypo-phosphorylation or mimicked hypo-phosphorylation by expressing RARαS77A mutant inhibited proliferation of cancer cells [17–21].